1. Field of the Invention
The invention relates to a motor construction unit for a submersible pump unit with an electric motor and a frequency converter connected in series, the frequency converter being arranged flush to the motor and having a first component including a power part, a second component including an intermediate circuit, and a third component including control electronics. A housing casing receives the frequency converter therein as an insert, the housing casing having an inner contour with a circular cross-section.
2. Description of the Related Art
Motor construction units of this type are used for submersible pump units which have a slimline and essentially cylindrical shape and are essentially cylindrical shape and are adapted to the predetermined restricted bore-hole dimensions. Such submersible pump units are for example known from DE 38 20 005 , to which U.S. Pat. No. 4,981,420 corresponds and EP 0 346 730 , to which U.S. Pat. No. 5,028,218 corresponds. With these submersible pump units there is integrated a frequency converter which allows the pump unit to be driven at high speed independently of the frequency and voltage of the electrical supply network and thus to achieve a high delivery output also with a comparatively small tube diameter or unit diameter.
A certain problem with such units which comprise an integrated frequency converter is to regularly lead away the waste heat arising in the power part of the frequency converter. With the pumps according to the initially mentioned state of the art this is effected via the delivery medium by forming within the unit a part-flow which is essentially used for the leading away of the heat arising in the frequency converter. The costs with respect to design required for this are quite high which is why one has also in the meantime gone over to leading away the heat not to the delivery fluid but to the housing of the unit since this is in connection with the surrounding delivery medium in a large-surfaced manner and therefore is particularly predestined for the leading away of this waste heat.
A problem is to lead away the waste heat to the housing or housing casing as a rule consisting of sheet metal. In DE 197 27 202, to which U.S. Pat. No. 6,022,196 corresponds, this is effected by allocating to the heat-producing componentry of the frequency converter elastic cushions which are filled with a heat-conducting means and which convey the heat from the corresponding componentry via the cushion to an inner housing or an inner shell which for its part is inserted into the housing casing formed of sheet metal. This construction type although it has proven itself, it is however quite complicated with regard to manufacturing technology since a shape-stable inner housing is required on which a head-conducting cushion may be supported in order to make possible an intensive heat transfer. This inner housing in manufactured of lightweight-metal profiles and as a whole together with the componentry located therein is inserted into the metallic housing casing. The latter may likewise be problematic since for achieving a large surfaced heat removal there is required a close a possible bearing of the inner housing on the housing casing which leads to high forces on inserting or pressing the inner housing into the housing casing. Since the housing casing is a formed sheet metal part which may not be retro-machined in a material-removing manner, alignment errors, even if slight, over the length of the housing are not to be completely ruled out, which may lead to considerable problems on insertion of the inner housing into the casing.
Against this state of the art it is the object of the invention to further develop a motor construction unit of the type according to the introductory part of the claim such that it is inexpensively manufacturable, in particular in large scale manufacture, and the previously outlined assemble problems are avoided.
According to the invention, a first heat distributor is heat-conductively connected to the first component, and has an outer contour which essentially corresponds to the inner contour of the housing casing and bears on the inner contour over the entire periphery of the first heat distributor.
The basic concept of the present invention is to do away with the heat-conducting contact between the inner housing and the housing casing and instead of this to provide one, or where required several heat distributors, which convey the heat directly to the housing casing. In order to achieve this the heat distributors in their outer contour are adapted to the inner contour of the housing casing so that they essentially over their whole periphery bear on the housing casing and thus ensure a large-surfaced heat transfer. Since only in the region of the heat distributor is there required a heat-conducting contact, the remaining parts of the insert may be freely configured. Thus one may largely do away with an inner housing or manufacture this of plastic or other material. Furthermore these further insert parts may be arranged with play within the housing casing which simplifies the assembly since on inserting only the friction between the heat distributor or heat distributors and the housing is to be overcome.
Preferably the head distributor is heat-conductingly connected to the first component, thus the component which contains the power part of the frequency converter is arranged at the motor-side end of the frequency converter. Power part is not necessarily to be understood as the power circuit but also where appropriate the power electronics of the input circuit. By way of this there result short conduction connections from the power part to the motor. Furthermore the conduction connections in a particularly advantageous further formation of the invention may be formed by the first component.
If on account of the constructional size of other demands further components of the frequency converter require a separate cooling, then it is useful to provide a further heat distributor which likewise essentially over its whole periphery bears on the housing casing and whose outer contour essentially corresponds to the inner contour of the housing casing. Advantageously with the provision of several heat distributors these are not arranged directly behind one another but at a significant distance to one another in order to simplify the assemble of the insert. With one embodiment which envisages two heat distributors these are advantageously arranged at both ends of the insert, where in the heat distributor for the first component, thus for the power part, is advantageously arranged next to the motor.
The first heat distributor for the power part comprises usefully a transverse wall on which the first component bears in a heat-conducting manner over a large area in order to ensure the heat removal towards the housing casing. This transverse arrangement of the first constructional unit offers particular advantages which are further described in detail below.
Apart from the first component which is usually designed as a semi-conductor component or encast semiconductor component, furthermore in particular in the coils of the frequency converter heat is set free which is to be led away. These coils of the frequency converter are preferably in each case incorporated into an axial recess of a heat distributor. Thus for example another coil may be incorporated into an axial recess provided in the heat distributor for the power part on the other side of the transverse wall.
The component which forms the intermediate circuit and which may where appropriate also comprise the input circuit or parts of the input circuit, as well as the control electronics (under this control electronics is to be understood in the broadest sense, thus also the componentry required for the control) are advantageously arranged on circuitboards which extend in the longitudinal direction of the motor construction unit. Usefully for each of the two components there is in each case provided one circuitboard. This arrangement has the particular advantage that all lead connections between the first component and the second component, between the second and the third component as well as between the first component and the third component may be formed by the first component itself. Such an arrangement is particularly favorable with regard to manufacturing and assembly technology since a large part of the lead connections within the frequency converter may be formed by the first component which considerably reduces the number of assembly steps. Furthermore by way of such an arrangement also the operational safety is improved since the number of soldering or plug connections may be reduced to a minimum. Preferably these lead connections proceeding from the first component are formed by sheet metal sections which are mechanically connected and held by way of a plastic mould body as will yet be described in detail by way of the embodiment example. This plastic mould body advantageously serves also for the fastening of the first component on the heat distributor. It may enclose or also completely accommodate the semiconductor element comprising the power part of the frequency converter.